Ok, I managed to get MySQL to install, thanks to Jacob's suggestion
below, but the DB_DIR was not created, mysql will not start even when "
/usr/local/share/mysql/mysql.server start" is executed manually, and no
errors are returned to the console. Do I have to create the DB_DIR
manually. I can't seem to find any post install instructions in the
ports working directory and I couldn't find any instructions or
documentation for the "proper" way to start mysql on boot and stop
mysql on shutdown.

I came from a FreeBSD background and I assumed that the installation of
mysql from ports would be almost the same (i.e. make install clean +
enable rc.d startup script). FreeBSD ports install does all the
required leg work except enabling the start up scripts for mysql. Does
a working installation of mysql on OpenBSD requires a bunch of post
install tasks or the port I'm using in an unfinished/broken state?